Thermal analysis of green algae for comparing relationship between particle size and heat evolved

Abstract

The thermal properties affected by particle size of microbial cell were investigated by the simultaneous thermogravimetry (TG) and differential thermal analysis (DTA). The particle size, which could affect the heat evolved, occurred from the combustion of the microbial cells. The model microorganism used in this study is Nostoc, a genus of flamentous, heterocystous, and cyanobacteria, known as a freshwater microalga, which can accumulate a large amount of lipid in the cell. As a result, the marked difference in heat energy between the different particle sizes of microbial sample was detected in the temperature range from 310 to 351°C. So, the two-step linear temperature program is used for resolving the overlapping exothermic peaks in the DTA curves in the temperature range from 310 to 315°C. The heat evolved from 45 μm-sized particle sample in this temperature range was 3.78±0.19 kJ/g which was 1.1-to 1.4-fold greater than those from the other particle size samples. The heat evolved occurred in 310-351°C was inversely proportional to the particle size of dried microbial cells. In conclusion, exothermic heat per dry sample mass (kJ/g) in the temperature range from 310 to 351°C is highly dependent on the particle size of dried microbial cell.

Characterization of fatty acid components from Tetradesmus obliquus KNUA019 (Chlorophyta, Scenedesmaceae) for a resource of biofuel production

“…Both exothermic DTA peak area and mass loss, as defined by TGA curves, were greater for the smaller undefined particles (< 50 μm). Little is currently known about how particle size affects heat production, exothermic DTA peak area, and TGA curves for a specific temperature ranges (Kang and Yoon 2015). In this study, heat liberation, exothermic DTA peak area, and mass loss in TGA curves in this temperature range were inversely proportional to the lipid content, which might contribute toward biofuel production in particle size of green algae samples.…”

“…Thermal analysis is widely used for analyzing minerals and ceramics substances (Ochiai and Ozao 1992). However, it can also be applied to green algae and is valuable for screening oleaginous green algae for thermal content (Kang and Yoon 2015). The lipid contents of green algae release heat when burnt at appropriately 25 min.…”

“…In this study, heat liberation, exothermic DTA peak area, and mass loss in TGA curves in this temperature range were inversely proportional to the lipid content, which might contribute toward biofuel production in particle size of green algae samples. Previous studies have reported that temperatures from 280 to 360 °C, using a two-step linear temperature program, produce exothermic DTA peak areas and TGA curves that can reflect the total lipid content (Kang and Yoon 2015). Thus, heat liberation, exothermic DTA peak areas, and mass loss in TGA curves could be explained by the volatilization of burnable materials, including components that may support biofuel production.…”

“…The heat evolved was measured as the area under the DTA peak using a zero baseline. Heat evolved in the temperature range between 280 and 360 °C was calculated as previously described (Kang and Yoon 2015).…”